A comparative study of lupeol extraction from a by-product of lupin processing by hydrophobic natural deep eutectic solvents and their precursor components

A series of hydrophobic natural deep eutectic solvents (HNADESs) have been employed to extract lupeol from lupin seed coat at 30 and 70 & DEG;C. The extraction yields have been compared with those obtained with conventional organic solvents. In general, lupeol extraction yields (LEYs) obtained when using HNADES are somewhat smaller than those obtained if organic solvents are used. However, the nature of the HNADES mixtures as green solvents represents a superior performance in terms of sustainability of the extraction process. Additionally, an investigation has been carried out in order to compare the LEYs obtained when using the HNADES mixtures with those obtained if the isolated precursor compounds are employed at a temperature (70 & DEG;C) where both HNADES and the corresponding precursor compounds are liquids. Surprisingly, LEYs for lupeol at 70 & DEG;C were found to be, in some cases, slightly higher if the precursor compounds are used in comparison with the proper HNADES mixtures. It seems that the unique properties of the HNADES mixtures are not enough to perform better as extractants in comparison with the isolated precursor compounds at moderate temperatures, at least for the case of lupeol from lupin seed coat. Some hints are presented to explain these results. Graphical Abstract: Lupeol from lupin seed coat by-product can be extracted with hydrophobic natural eutectic solvents and their precursor compounds.image